1. Field of the Invention
This invention relates to a device for effecting mechanical coupling between a movable part of an apparatus and a linear displacement transducer which is required to signal an operating position of that movable part.
2. Discussion of Prior Art
In particular a device according to the invention is intended to signal the operating position of a linearly movable element in an actuator for deploying and stowing thrust reversers on a gas turbine engine. Such an actuator is shown in U.S. Pat. No. 3,621,763 and includes a rod which is threadedly engaged with an output element of the actuator and which rotates, but does not translate, as the output elements moves linearly. The rod is required to provide an indication of the position of the output element, relative to a fixed part of the actuator. However if a connection between the output element and a part upon which it acts is such as to permit rotation of the output element relative to the aforesaid fixed part, the threaded rod will give a false position indication.
European patent application 0303399 discloses a linear position transducer which is responsive to the rotations of the threaded stem, and hence to the actuator output position, and shows a device by means of which movement of an input element of the transducer is arrested at predetermined limiting positions thereof. Since the limiting positions and the transducer are stationary relative to the fixed part of the actuator, the transducer is effectively reset at each end of actuator travel.
It is a disadvantage of the device shown in EP-A-0303399 that the resetting positions of the transducer are dependent on the initial axial position of the latter relative to said fixed part. The transducer thus requires precise initial positioning which can be achieved only during initial assembly or by means of factory overhaul. The present invention provides a device by means of which replacement of a transducer can be effected without affecting the resetting positions thereof.